Chemotherapy after gastric cancer surgery can inhibit the growth of tumor and prolong the patient’s survival, but nowadays there is no specific drug for chemotherapy, so the clinical treatment is comprehensive treatment, surgical treatment first, followed by chemotherapy. The first step of comprehensive treatment for gastric cancer is to remove the tumor surgically to remove the root cause of propagation, and after that, the regional lymph nodes can be cleared, and the lymphatic metastases visible during the surgery as well as the lymph within the regional area will be routinely cleared. The danger of malignant tumor is that malignant tumor is composed of cells, because the cells are invisible to the naked eye, so some small cancerous cells cannot be detected in time during surgery, so we hope that chemotherapy will be given after surgery.